Semiconductor devices are used in a variety of electronic applications, such as personal computers, cell phones, digital cameras, and other electronic equipment. Semiconductor devices are typically fabricated by sequentially depositing insulating or dielectric layers, conductive layers, and semiconductive layers of material over a semiconductor substrate, and patterning the various material layers using lithography to form circuit components and elements thereon. Many integrated circuits are typically manufactured on a single semiconductor wafer, and individual dies on the wafer are singulated by sawing between the integrated circuits along a scribe line.
In the semiconductor manufacturing process, an interconnect structure is used to form connections between devices. With more and more devices on a chip with high integrity, the early-stage single-layer metallization process had been improved to form multiple layers of connections. Two layers, three layers, or even four layers of connections are formed in the semiconductor devices.
Although existing interconnect structures have been generally adequate for their intended purposes, they have not been entirely satisfactory in all aspects.